Refrigeration



June 17,1941.

J. c. coNsLl-:Y 2,246,244

REFRIGERATION Filed June 19, 1940 s sheets-sheet 1 CONDENSERJ on. ST1LL! 1 0 nvenfor (Ittornegs June 17, i941.

J. C. CONSLEY REFRIGERATION Filed June 19, 1940 3 Sheets-Sheet 2 TO PUMPINLET :inventor 302W C?. @o wslew/ a Q i,...

l attorneys 3 Sheets-Sheet, 3

|||||l|l||||||||||||||||l JUN 17, 1941. J. c. coNsLEY REFRIGERATIONFiled June 19, 1940 v Illl 58 Patented ,June l,l 1941- S ,PATENTormone:A

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BEFRIGEEATION Jenn c. cennenrerk, rs., assigner to York ree Corporation,York, Pa., a corpora- Machinery tion of Delaware application :une 19,1940', sensi No. 341,385

e io clame.

This invention relates to refrigeration 4and par. ticula'rly tomaintenance of oil in the cranlncases of a plurality of compressorsconnected between icl; ca -ns) is shown simply as atypical oil lrecoveryscheme without implication of limitation to that or any other oilrecovery scheme.

the same suction or discharge lines and cone with which lubricating oilis freely miscible in all l proportions so that gravity separation isimpracticable and tendencies to pump oil'with the v refrigerant areaccentuated,A

Where a large number ofcompressors are used (and installations usingeight are now in commercial fuse to secure extreme exibility and freedomfrom severe vibration). it isvery dimcult to assure adequate supply ofoil to all compressor crank cases. Connection of the crank cases by oiland gas pressure equalizing lines will 1 not suice because pressurediiferences which inevitably exist between idle and active compressors,particularly compressors which` have just nstarted up, cause the idlecompressors to rob Vthe active ones of oil. f

The system of the Zercher Patent 2,076,332 will operate but requiresperiodic shut-'downs to per- The seperated en :e fed te e sumpmaintained under suction line pressure and preferably of substantialhorizontal area so that it may supply sumclent oil for all crank caseswith a reduction of its own oil level not exceeding the oil levelvarlation permissible in the crank cases. Bo dimensioned. 'the sump maybe set ata height so low that, with the minimum lquantity of oil, thesump oil level is little, if any, above the lowest permissible crankcase oil level. This sump can be -smaller and can lbe set higher, but atthe risk' that a leaky oil return valve will cause serious over feeding.

The low setting of the tank silords only a'low gravity feed of oil andis practicable because q strainers are used in the suction connection ofmit oil equalization tonccur and this is not practicable with largeinstallations which remain in almost continuous operation. at least atpart capacity. v

All compressors pump out some oil with refrigerant. With certaintypespiwevaporators the oil tendsto accumulate in the evaporator.Various schemes, some of which use stills, have been devised to separatethis oil from refrigerant and 'thus recoventhe oil. Other types ofevaporators discharge the oil to the suction line, from which it may bedrained to a sump andagain used.

'I'he problem in multiple compressor installations. regardless of theparticular system of oil recovery, is to assure delivery of therecovered oil in proper quantity to all crank cases, of both active andidle compressors, maintain an adequateA the compressors with the resultthat the 'suction space on the compressor side ofthe strainer of arunning compressor is at a lower pressure than is the suction line. Nopressure equaliuingconnection is provided between the crank cases ofdifferent compressors, but the crank cases of all compressors are invirtually free prsure equalizingcommunication with their respectivesuction spaces.- Thus in any running compressor the crank case pressureis lower than pressure inthe suction line. The amount that 'it is lowerdepends on how much the particular strainer retards now, l but in anycase the differential is suilicient to assure oil ilow from the sumpmaintained at suction line pressure tothe crank case of an activecompressor, even when the gravity ilow of oil level would be slight.Float valves subject to oil levels in corresponding crank cases controlflow of oil from the sump, each to a corresponding crank case. The oatscan be in the 'crank cases, but I prefer to locate them in separatechambers to stabilize their action.

Where force ileedy lubrication. is used, refinements are possible butnot always required. For example. part of the oil discharged by eachpump may be returned to the sump, thus assuring circulatory flow andprotecting against over feeding by a leaky iioat valve. when this oilreturn scheme is used, the float valve may be contrived so as toapportion the oil drawn by the pump so that a variable part is drawnfrom the crank case and the remainder'irom the sump. x

Practical embodiments of the invention will now be described byreference to the accompanying.drawings,in which: e

Figure 1 is a diagrammatic elevation showing three six-cylindercompressors of the so-called W-type, together with the refrigeratingcircuit and the oil recovery circuit.

Fig. 2 is an axial section through one of the compressors shown in Fig.1.

Fig. 3 is a section on line 3--3 of Fig. 2.

Fig. 4 is a View similar to a portion of Fig. 1 showing a modificationof the oil return connection.

Fig. 5 is a section through a type of float valve which may besubstituted for those shown in Figs. 1 to 4 inclusive.

Fig. 6 is a diagram showing the simplest possible embodiment of theinvention.

Fig. 7 is an axial section of the check valve and restricted bypassaffording communication between the compressor suction and the crankcase.

Referring first to Fig. 1, the refrigerant circuit will be traced. Threesix-cylinder W-type compressors, indicated Iby the reference numeralsCI, C2 and C3, have their suction connections in communication with acommon suction line II and their discharge connection in communicationwith a common high pressure discharge line I2, through which hotcompressed refrigerant ows in the gaseous phase. Most of this hotrefrgerant flows through the branch I3 to condenser I4, which may beassumed to be of the water-cooled shell-and-tube type. though it maytake any suitable form.

From the condenser I4 refrigerant passes by way of an expansion valveI5, here shown as a high side float valve, and liquid line I6 to anevaporator I1. This may be assumed to be of the shell-and-tube type inwhich the liquid to be cooled is circulated through heat exchange tubeswithin the shell. No effort has been made to illustrate such tubesbecause the particular construction of the evaporator is not a featureof the invention, nor is it novel.

From the bottom of the evaporator Ii the branch pipe I8 leads to acirculating pump I9 which delivers most of the pumped refrigerant to aspray pipe 2i within the evaporator shell I1. The sprayed refrigerantflows over the aforesaid heat exchange tubes in the evaporator.Refrigerant evaporated by heat abstracted from the tubes Will .pass offby way of the branch 22 to the suction line I I.

There is an oil still comprising a cylindrical shell 23 having near oneend (the left-hand in this case) a partition 24. A branch from. thedischarge of the circulating pum-p I3 leads to a heat exchange coil 25which zig-zags back and forth within the `shell 23 at the right of thepartition 24 and finally discharges at 26 into the space within theshell to the left of this partition. The suction line II is in directcommunication with the top of the space to the left of partition 24 and-from the bottom of this space an oil line 21 leads to the cylindricaloil sump 23. A branch ofthe high pressure refrigerant line I2communicates with and delivers hot gasecus refrigerant to the interiorof shell 23 to the right of the partition 24. A high side float valve 23controls the delivery of liquefied refrigerant from this space to theevaporator I1 by way of connection 3l.

Assuming that the compressors discharge com- The high side float valveI5 passes the mixture to the evaporator I1 as the liquid accumulates andsince only the refrigerant evaporates in the evaporator I1, there is atendency for oil to accumulate in the evaporator.

The -pump I9 draws oil and refrigerant mixture from the evaporator,circulates part of it back to the evaporator through the sprays, butcirculates a small quantity through the coil 25. At the same time alimited quantity of hot gaseous refrigerant enters the shell 23 to theright of the partition 24 and delivers heat to the oilrefrigerantmixture owing through the coil 25. The hot gaseous refrigerant is cooledand thus condensed to liquid, and as it condenses is delivered by thehigh side float valve 29 to the evaporator. The oil-refrigerant mixtureflowing through the coil 25 is heated so that when it discharges at 26under suction pressure the refrigerant evaporates and ows off to thesuction line Il, while the oil drains through the pipe 21 tothe oil sump28. This still scheme, using hot gas to distill refrigerant from theoil, is the invention of another and is shown here simply as aconvenient and effective means Ifor separating the oil from therefrigerant on the lowr pressure side of the refrigerant circuit. Otherlow side oil recovery schemes are I mown and might be used for the samepurpose, it being understood that the present invention has to do withdistribution of oil to the various compressors and is not limited to usewith any particular system of recovery.

To assure thatthe oil sump 28 operates at suction line pressure, abranch of the suction line I I is connected with the top of the sump at32.

Each of the compressors CI, C2 and C3 is shown as of the formillustrated in Figs. 2 and 3, but the compressors may assume any -formhaving an oil retaining crank case or oil bath. The W-type compressor ischosen -for illustration simply because this type usually has force feedlubrication and is being used extensively in multiple installations.

The crank case of the compressor is indicated generally at 33 and itsform is clearly shown in the drawings A double-throw crank shaft,indicated at 34, is mounted at one end in an enclosed bearing 35, and ismounted at the other end in a bearing generally indicated at 36 andprovided with a gas seal, not illustrated in detail because itsconstruction is not a feature of the present invention. A grooved pulley31 is mounted on the end of the crank shaft and serves as the meansthrough which the compressor is driven. 'Ihe usual drive involves theuse of an electric motor for each compressor with multiple V-belts forwhich the grooved pulley 31 is intended.

Six cylinder-sleeves 38, mounted in pairs in three radiating Iplaneswith respect to the axis of the crank shaft, are fixed in a cylinderhouspressed refrigerant, together with some oil,`

through the line i I2, the major part of the hot gaseous refrigerant andoil .passes to the condenser I4 where the refrigerant assumes the liquidphase and mixes completely with the oil.

ing 33 whose form is clearly shown in Figs. 2 and 3. The housing formsa. suction chamber 4I with which the suction line II communicates by wayof the suction -port 42. In this suction port is mounted a suctionfilter or strainer 43 which has a Ythrottling eiect whose intensityvaries somewhat with the condition of the filter. The pressuredifferential increases if the lter becomes partially clogged.

'Ihe cylinder bushings 38 are provided with elongated side slots 44which are inlet ports communicating with the interval between the twoends of pistone 4I.- These pistons are of the 33 and the suction chamber4|.

hour glass type, that is to say, they' have a head 46 provided with apacking ring 41, a reduced middle to which. the pitman is connected, anda The upper ring is customarily a venoil scraping ring. These oilringsare not pack` ing rings so that pressure equalization occurs past thembetween the interior of the crank case In addition there is a restrictedport 4|! which is constantly Aopen and a ball check valve 50 which opensto permit free ,flow from suction chamber 4| to crank case 33. The portand check valve are associated with the fitting 68 illustrated in Fig.7.

The inlet valves 49 are mounted in the piston head 45 and are of theannular plate type. The

discharge valves 5| are of the ported disc type,

are confined by va retainer 52 and are mounted in the cylinder head 53which is bolted to the cylinder housing 39 and serves to retain thecorresponding cylinder bushing 38 in place. Over each pair of sidecylinder heads is a cap 54 and these communicate by passages 55 and 56with a similar cap 51 which overlies the heads of the two verticalcylinders. Cap 51 has a 'discharge connection 58 leading to the highpressure line l2.

The mechanism illustrated at 59 is a relief valve for relievingexcessive discharge pressure and the mechanism generally indicated at 6lis an unloader mechanism whose function is to unload partially theadjacent cylinders of a pair by opening an unloader port located at partstroke of the piston. There commonly is one of these unloaders for eachpair of the four oblique cylinders of each compressor. They may beoperated in any desired order by an oil pressure mechanism not shown indetail. Various other unloader mechanisms are known and may be used. Thepresence of the unloader is important only because it is an unfavorablefactor as far as oil distribution is concerned, since it disturbs thesuction pressure in the compressor. The present inventionoperatessuccessfully despite the use of unloaders.

'I'he unloader comprises a sleeve valve 62 which is urged by a spring 63toward the unloading position shown in Fig. 3, in which position .itexposes the unloader port 64. The unloader valve is closed to load thecompressor by admitting oil under pressure below the piston 65throughthe connection 65. The mechanism which supplies the oil underpressure to operate the piston 65 is not illustrated.

The oilsump 28 is an elongated horizontal cylinder preferably, but notnecessarily, so .dimensioned that when it is vllled with the 'maxih mumvolume of oil to the line A-B it can not overll the crank cases of thecompressors C I, C2 and C3. However, if drawn upon by all the crankcases, it will furnish sumcient oil with a fall of oil level to the lineC-D to maintain a safe level of oil in all the crank cases. Thiseliminates, or at least minimizes, risk of over feeding which may becaused by a leaky float valve 89.

Leading from the bottom of the sump 28 is the oil supply line 61 whichhas three branches 68, each leading to a corresponding float valve 69.'I'hese are shown as mounted in separate housings having top and bottomconnections 1I and 12 with the related crank case. but the floatmechanism can be, and in commercial installations often is, mountedwithin the crankcase.

The oat is indicated at 13 and the lloat valve opens when the oil levelis low and closes completely at the maximum desired oil level.

The oil connections just describedare suicient I to assure proper oilfeed, but when `force feed lubrication is used certain refinements arepossible. The compressor shown in Figs. 2 and 3 has beyond the bearing35 a housing 14 which includes an oil pump of the gear type, the gearsbeing indicated at 15 and 16 in Fig. 2. Gear 'I5 is driven from the endof the crank shaft 34 and drives the gear 16. The pump draws oil fromthe bottom of the crank case through a connection 11 and discharges itthrough a connection 18 to an oil lter 19, from which it passes to theoil distributing line 8| which delivers the oil to the various bearings,to the shaft seal, and to other components, according to principles wellunderstood in the compressor art and not involved in the presentinvention.

A pressure regulating valve 8,2 is provided and conveniently is theusual loaded relief valve which returns excess oil from the pumpdischarge to the crank case whenever discharge pressure exceeds a setvalue.'

With a compressor equipped as above described, itis possible to providefor the return of a part of the oil from each compresser to the sump 28,thus correcting any over feed which might occur. One way of doing so isshown in Fig. l. From each discharge line 18 a restricted branch 83leads to oil return line 84, which discharges into the top of sump 28.

To avoid use of a return line 84 recourse may4 be had to the arrangementshown in Fig. 4, in which similar parts are numbered as in Figs. 1-3with the letter a. Here `a restricted line 83a connects the pumpldischarge line 18a with the supply branch 68a, but the arrangement shownin Fig. 1 is considered better practice.

In any case where the connection 83 or 83a is used I may adopt a.modified form oi' float valve shown in Fig. 5. In this gure the housingis -generally indicated at 6917, the supply branch from the oil sump 28is shown at 68h, the intake line of the oil pump is shown at 11b, andthe two connections to the crank case are indicated at 1lb and 12b. Thusparts including the letter b correspond to similarly numbered parts inFigs. 1 to 4 inclusive.'

The housing 69h contains two-(chambers, a iloat chamber 85 and a valvechamber 86 which is at one end and occupies only part of the width ofthe housing 69h, as indicated. Supply connection 68h leads to a valveseat 81 at one side of l tween chambers 85 and 86, and carries, xed to'it, the arm of float 13b.

When oil level isvlow in the crank case, the pump draws oil from the'sump 28. When oil level reaches the maximum desired, the pump drawsexclusively from the crank case. Between these limits there is anapportioning action. ThisA float valve causes the lubricating pumps toexert suction on the supply line, when such action is desirable, -sothat gravity feed flow is.

assisted by the pumps.

It the oil sump be kept at suction line pressure, and if the crank casesare at compressor suction pressure, and if there is suiilcientthrottling at the compressor intake to assure that crank case pressurefor any running compressor will be slightly lower than suction linepressure, the invention can be applied provided the crank cases areisolated from one another except for connection with a common suctionline. Force feed lubrication increases the problem because it increasesoil discharge, but neither it nor the oil return connection 83 or 83a isessential to the invention in its broadest aspects.

To emphasize this reference is made to Fig. 6. The sump 28e has the sameconnections 21c and llc as does sump 28 in Fig. 1. Compressors C4, C5and CB are splash lubricated and are connected to a common dischargeline I2C. The refrigerating circuit and oil recovery would be the sameas in Fig. 1. All crank cases are at compressor suction pressure andsuction strainers or equivalent throttling means are interposed betweensuction line llc and each compressor.

The parts 61e, 68e and 69o correspond to similarly numbered parts inFig. 1 and the elevation and capacity of the sump 28e may be asdescribed with reference to Fig. 1.

Such a system will operate successfully because protected against suchrise of crank case pressure as might, if allowed to exist, cause loss ofoil.

In any case where the lubricating pump returns some oil to the sump, themounting of the sump at a low elevation is less important than in caseswhere there is no provision for correcting for overfeed to the crankcase. Such overfeed can be caused by a leaky float valve.

When the apportioning float valve of Fig. 5 is used the maintenance ofstrict suction line pressure in the sump is less important than in otherembodiments because the lubricating pumps exercise a denite suction feedon oil from the sump.

In the claims I shall refer to compressor intake pressure (the pressureon the compressor side of the intake lter) to differentiate from suctionline pressure.

While the crank case usually retains the bath of lubricant for eachcompressor, thebath is the important thing and in certains claims Ishall use this ,term to avoid any implication that the crank casenecessarily retains the oil bath, other arrangements being knowri andoccasionally used.

I claim:

1. A refrigearting circuit containing volatile refrigerant andcomprising a plurality of compressors connected in parallel between asuction line and a discharge line, and a condenser, expansion valve andevaporator connected in the order stated between the discharge line andthe suction line, said compressors being each of the type having a crankcase subject to compressor intake pressure and containing oil forlubricating the compressor; flow retarding means interposed between thesuction line and each cornpressor intake and serving to cause crank casepressure of any operating compressor to fall below suction line pressureas an incident to such operation; means for recovering from said circuitoil leaving the compressors with refrigerant; a sump to which saidrecovered oil is delivered; means connecting said sump, at a level aboveoil therein, with said suction line; and liquid level controlled meansresponsive to the refrigerant and comprising a plurality of compressorsconnected in parallel between a suction line and a discharge line, and acondenser, expansion valve and evaporator connected in the order statedbetween the discharge line and the suction line, said compressors eachincluding a crank case subject to compressor intake pressure andcontaining oil, and an oil pump which draws oil from the compressorcrank case and discharges it under pressure to parts of the compressor;ilovv retarding means interposed between the suction line and eachcompressorintake, serving to cause crank case pressure of any operatingcompressor to fall below suction line pressure as an incident to suchoperation; means for recovering from said circuit oil leaving thecompressors with the refrigerant; a sump to which said recovered oil isdelivered; means connecting said sump, at 'a level above the oiltherein, with said suction line; liquid level controlled meansresponsive to levels of oil in corresponding crank cases and controllingflow of oil from the sump to each crank case; and a restrictedconnection from the discharge of each oil pump to said sump.

3. A refrigerating circuit containing volatile refrigerant andcomprising in combination, a plurality of compressors connected in.parallel between a suction line and a discharge line, and a condenser,expansion valve and evaporator connected in the order stated between thedischarge line and the suction line, said compressors having crank casescontaining lubricating oil, the crank cases each being subject to theintake pressure of the corresponding compressor; force feed lubricatorpumps, one for each compressor; means for recovering from the circuitlubricating oil which leaves the compressors with refrigerant; a sumpfor collecting such oil; liquid level controlled valves, one responsiveto the oil level in each crank case and controlling the supply of oil tothe lubricator pump for the corresponding compressor, and serving as thecrank case oil level rises and falls to vary the relative proportion ofoil drawn from the crank case and from said sump; and connections fordischarging a, limited portion of the lubricating oil delivered by saidlubricator pumps to said sump.

4. The combination of a refrigera'ting circuit of the compressorcondenser evaporator circuit type including a plurality of compressorsconnected in parallel in said circuit, each compressor includinglubricant bath retaining means suoject to intake pressure of thatcompressor; means lfor.' recovering from the circuit lubricant leavingthe compressors with .the refrigerant; a, sump for collecting suchrecovered lubricant; means for maintaining said sump at the suctionpressure in the circuit; ow retarding means in advance of eachcompressor intake for causing the intake pressure of any compressorwhich is operating to be maintained slightly below the suction pressureof the circuit; and liquid level -controlled means, one responsive tothe level of the lubricant bath in each compressor and controlling thedelivery of lubricant to said bath from said sump.

5. The combination defined in claim 4 in which each compressor includesa lubricating pump drawing from .the lubricant bath in that compressor,and means are provided for discharging a portion of the oil delivered byeach such pump to said sump.

6.The combination of a refrigerating circuit of the'v compressorcondenser evaporator circuit type containing -a volatile refrigerant,the com' pressor thereof having a lubricant bath; means for recoveringfrom said circuit lubricant leaving said compressor with refrigerant;` asump for collecting the recovered lubricant; a lubrieating pumpassociated with said compressor, said pump drawing lubricant from saidbath and having a restricted connection for delivering a for recoveringfrom said circuit lubricant -leaving said compressor with refrigerant; asump for collecting the recovered lubricant; a lubricating pumpassociated with said compressor and having a restricted connection fordelivering a part of the oil pumped thereby to said sump, the mainportion of the remainder being returned to the bath after performing itslubricating function: and liquid level contrlledvalve means responsiveto the level of lubricant in said bath and controlling .the supply oilubricant to said pump, said Avalve means serving to connect said pumpto draw lubricant in varying proportions from said sump and said bath asthe lubricant level in the bath varies.,

8. The combination of a refrigerating circuit of 'the compressorcondenser evaporator circuit type con-taining -a volatile refrigerant,thecompressor thereof having a lubricant bath; means for recovering fromsaid circuit lubricant leaving said compressor with refrigerant; a sumpfor collecting the recovered lubricant, said sump being subject to7pressure in the low pressure side of the circuit and located at suchelevation relatively .to the elevation of the bath as to afford a slightgravity feed tendency from the sump to the bath, the lubricant bathbeing subject to compressor intake pressure;,1iquid level controlledmeans responsive to the level of lubrilubricant from the sump to thebath: and flow restricting means between the low pressure side of saidcircuit and the compressor intake sutilcient to cause modera-tedepression of intake pressure below such suction pressure when thecompressor is operating, whereby .the tendency of flow from the sump to.the bath is accentuated.

9. The combination of a refrigerating circuit of the compressorcondenser evaporator circuit type containing a volatile refrigerant, thecompressor thereof having a lubricant bath; means for recovering fromsaid circuit lubricant leaving said compressor with refrigerant; a sumpfor collecting the recovered lubricant, said sump being subject topressure in the low pressure side of the circuit and located at suchelevation relatively to the elevation of the bath as to afford a slightgravity feed tendency from the sump to .the bath, the lubricant bathbeing sub ject yto compressor intake pressure; liquid level 'controlledmeans responsive to the level of lubricant in said bath and controllingthe supply of lubricant from the sump to the bath; flow re- -strictingmeansfbetween the low pressure side 'of said circuit and the compressorintake suiiicient to cause moderate depression of intake pressure belowsuch 'suction pressure when the compressor is operating, whereby .thetendency of ow from the sump to the bath is accentuated; and meansoperative when the compressor runs to .deliver lubricant inA limitedquantity continuously sors; means for collecti from the bath to thesump.

'10. The combination of a refrigerating cir-L cuit inclusive ofcondensing means, evaporator means, and a plurality of compressorsconnected in parallel relationship in said circuit, each such compressorincluding a lubricating oil bath subject to the intake pressure of thatcompressor and isolated from the lrths of other compresg oil from saidcircuit and storing it under'the pressure prevailing in the suction sideof the circuit; intake ow restricting means associated with the'compressor intakes for causinglthe intake pressure oi'- an operatingcompressor to fall belowthe pressure prevailing in said suction side;and individual valve means responsive to the level of oil in the bath ofa corresponding compressor for supply@ 5g ing oil from said oilycollecting means to respective baths to maintain theoil levels therein.

JOHN C. OONSLEY.

cant in said bath and controlling the supply of

